From: Eric Blake <eblake@redhat.com>
Date: Fri, 17 Sep 2010 14:29:16 +0000 (-0600)
Subject: fdutimensat: drop atflag validation
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=18aae5b74420237d8c827e7c68312c5b71d659dc;p=pspp

fdutimensat: drop atflag validation

* lib/fdutimensat.c (fdutimensat): Allow AT_SYMLINK_NOFOLLOW even
with valid fd, to close a race scenario where futimens is
unsupported and FILE was replaced by a symlink.
* tests/test-fdutimensat.c (do_fdutimens, main): Adjust test
accordingly.
Suggested by Paul Eggert.

Signed-off-by: Eric Blake <eblake@redhat.com>
---

diff --git a/ChangeLog b/ChangeLog
index 624e412221..54319d5c5d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2010-09-17  Eric Blake  <eblake@redhat.com>
+
+	fdutimensat: drop atflag validation
+	* lib/fdutimensat.c (fdutimensat): Allow AT_SYMLINK_NOFOLLOW even
+	with valid fd, to close a race scenario where futimens is
+	unsupported and FILE was replaced by a symlink.
+	* tests/test-fdutimensat.c (do_fdutimens, main): Adjust test
+	accordingly.
+	Suggested by Paul Eggert.
+
 2010-09-16  Bruno Haible  <bruno@clisp.org>
 
 	unlockpt: Fix declaration within GNULIB_POSIXCHECK.
diff --git a/lib/fdutimensat.c b/lib/fdutimensat.c
index 77f893bb3b..0219a78326 100644
--- a/lib/fdutimensat.c
+++ b/lib/fdutimensat.c
@@ -35,8 +35,8 @@
    use just futimes (or equivalent) instead of utimes (or equivalent),
    and fail if on an old system without futimes (or equivalent).
    If TIMESPEC is null, set the time stamps to the current time.
-   ATFLAG must be 0 if FD is non-negative; otherwise it may be
-   AT_SYMLINK_NOFOLLOW to operate on FILE as a symlink.
+   ATFLAG is passed to utimensat if FD is negative or futimens was
+   unsupported, which can allow operation on FILE as a symlink.
    Return 0 on success, -1 (setting errno) on failure.  */
 
 int
@@ -44,20 +44,8 @@ fdutimensat (int dir, char const *file, int fd, struct timespec const ts[2],
              int atflag)
 {
   int result = 1;
-  if (atflag & ~AT_SYMLINK_NOFOLLOW)
-    {
-      errno = EINVAL;
-      return -1;
-    }
   if (0 <= fd)
-    {
-      if (atflag)
-        {
-          errno = EINVAL;
-          return -1;
-        }
-      result = futimens (fd, ts);
-    }
+    result = futimens (fd, ts);
   if (file && (fd < 0 || (result == -1 && errno == ENOSYS)))
     result = utimensat (dir, file, ts, atflag);
   if (result == 1)
diff --git a/tests/test-fdutimensat.c b/tests/test-fdutimensat.c
index 67f03bbb50..80eb373d00 100644
--- a/tests/test-fdutimensat.c
+++ b/tests/test-fdutimensat.c
@@ -53,6 +53,7 @@ do_fdutimens (char const *name, struct timespec const times[2])
     fd = openat (dfd, name, O_RDONLY);
   errno = 0;
   result = fdutimensat (dfd, name, fd, times, 0);
+  ASSERT (fdutimensat (dfd, name, fd, times, AT_SYMLINK_NOFOLLOW) == result);
   if (0 <= fd)
     {
       int saved_errno = errno;
@@ -116,9 +117,6 @@ main (void)
   fd = creat ("file", 0600);
   ASSERT (0 <= fd);
   errno = 0;
-  ASSERT (fdutimensat (fd, ".", fd, NULL, AT_SYMLINK_NOFOLLOW) == -1);
-  ASSERT (errno == EINVAL);
-  errno = 0;
   ASSERT (fdutimensat (fd, ".", AT_FDCWD, NULL, 0) == -1);
   ASSERT (errno == ENOTDIR);
   {